Condensing system



Jan. 17, 1933. J s rr 1,894,284

CONDENSING SYSTEM Filed Sept. 19, 1930 INVENTOR John H.5mich BY am ATTORNEY absolute pressure in the condenser. over, during perlods when the turbine is carremoval from the condenser casing.

Patented Jan. 17, 1 933 nrsn stars PATENT oFFicE' ELECTRIC 8a MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONDENSING SYSTEM Application filed September 19, 1930. Serial No. 483,087.

My invention relates to condensing systems, more specifically to a method of operating a surface condenser in conjunction With a steam turbineor other prime mover apparatus, and it has for an object to so operate the condenser that, not only during periods of full load, but during periods of very light load as well, a high condensate temperature Will be maintained.

Modern surfacecondensers are ordinarily so constructed and arranged that, under normal operating conditions, the condensate will be withdrawn from the condenser at a relatively high temperature, or in other words, a temperature substantially equal to the temperature corresponding to the vacuum or the Howrying a very light load or no load, as for in stance, when operated as a standby turbine, at which times only suhicient steam is admitted to keep the turbine in motion, the amount of water circulating through the condenser and the amount of condensing surface maintained active thereby is so large in proportion to the amount of steam condensed that the temperature of the condensate is depressed to a point considerably below that maintained during normal operation. During such periods of light load, not only is the temperature of the condensate depressed, but substantially the same amount of energy is expended in circulating cooling water through the condenser as under conditions of normal load. 1

The tube nests of the types of surface condensers now being largely used are, usually, divided into a condensing section and a cooling section. In other words, they are so constructed and arranged that one portion of the tube nest acts normally to condense the entering steam while another portion of the tube nest acts primarily to cool the air and non-condensable gaseous media prior to its In certain instances, the section of the condenser devoted to cooling the air may be enclosed in a shell or casing separate from the section acting to condense the steam. As will appear hereinafter, my invention is equally applicable to the type of condenser which i the condensing and cooling sections are both included in one shell or casing and to the type in which they are included in separate casings.

I have, therefore, conceived of a method of operating condensing systems duringperlods of llght load or substantially no ioad which results in maintaining the condensate at a relatively high temperature and in reducing the amount of energy expanded in circulating the cooling Water through the condenser. I accomplish these results by circulating cooling Water only through the cooling section of the condenser during periods of extremely light or substantially no loads. At such times, the cooling section acts as the entire condenser, no cooling Water being circulated through the condensing section of the condenser. Therefore, the amount of water passing through the tube. nest is not in excess of that required to condense the steam and does not act to abnormally depress the' temperature of the condensate emerging from the condenser. In addition,- the amount of cooling water being circulated through the condenser during periods of light loads having been reduced, the energy necessary to pump or circulate such cooling water is correspondingly minimized.

A more specific objectvof my invention is, therefore, to provide a method of operating surface condensers having the tube nest thereof divided into condensing and cooling groups, which method will maintain a high condensate temperature during periods of extremely light load.

A still further object of'my invention is to minimizethe amount of energy expended in circulating cooling 'water through a condenser by shutting off entirely the supply of cooling water to the condensing section of the tube nest during periods of light load and by utilizing the cooling section of the tube nest for condensing as Well as cooling purposes.

Still another object of my invention is to.

provide means for insuring that the tubes of the condensing section of the tube nest are.

protected by being filled with water during forming a .part of this application, in which:

Fig. 1 is a diagrammatic view of one form 1 of power plant ,unit in which my invention may be practiced; p I Fig. 2 is across-sectional view through the inlet water box of the condenser shown in Fig. 1, looking toward the tube sheet;

Fig. 3 is a cross-sectional view of the'tube nest of the condenser; and,

i Fig. 4 is a cross-sectional view of the outlet water box of the condenser. 9 Referring to the drawing, 1 show, in 1, a unit of power plant which is capable of being operated as a standby unit, and comprising a turbineor Jrime mover 11, driw ing an electric current generator 12. The

I latter is connected by means of leads'13 to-a power circuit 14, and a condenser 15 isconnected to the exhaust outlet 16 of the turbinefor receiving steam exhausted therefrom. Steam enters the turbine 11 by way o't-a pipe 17 and a governor valve 18, passes through the turbine, delivers its available energy, and passes out by way of the exhaust connection 16 and enters the condenser 15 through the inlet 19. I

The arrangement of the tube nest in the shell of the condenser 15 may be, for example, of conventional radial-flow design. It may comprise a shell 21, a tube nest 22 disposed longitudinally within the shell and spaced eccentrically therein, as illustrated in Fig. 3. An inlet water box 23, as shown in Fig. 2, is disposed at one end of the shell and an outlet water box 24:, as shown in Fig. 1, is disposed at the other end of the shell.

Referring to Fig. 3,the tube nest 22 is divided into a condensing section 25 and a cooling section 26. The cooling section 26 occupies a central position in the lower half of the tube nest. It is separated from the condensing section by longitudinally-extending vertical baffles 27 and an arcuate balfie 28 which is disposed in a substantially horizontal position over the battles 27.-and forms a cover to prevent condensate falling into the cooling section from the condensing tubes above. Openings 29 are provided at intervals along the upper and lower margins of the baffle plates 27 to provide communication between the condensing section and the cooling section. The inlet water box is divided into an outer chamber 31 serving to conduct cooling wat r to the tubes of the condensing section 25, and

- an inner chamber 32 serving to conduct cooling water to the tubes of the cooling section 26. The outer chamber 31 is supplied with cooling water through a pair of inlet ducts 33 while the inner chamber 32 is supplied through an inlet opening 34. Cooling water is supplied to the ducts 33 and the inlet 0 aening 34 from a header or conduit 35 which is supplied by a pump (not shown). The header 3-5 embodies branches 36 which communicate with the ducts 33 through valves 37, and an additional branch 38 which communicates directly with the inlet opening 34. I

The cooling water enters the tubes of each section of the tube nest and flows therethrough to the outlet water box 24 which forms a singlechamber 11 at the other end of the tube nest common to both the cooling and condcnsing tubes and receives cooling water from both. The outlet water box 24 is provided with a main exit connection as controlledby a main valve 13 and an auxiliary exit connection id controlled by an auxiliary valve 45. A standpipe 46 is provided in the outlet water box and formsa continuation of the auxiliary exit connection 44 so as to cause the cooling water which is to pass out by way otthe auxiliary connection to be drawn from p the upper part of the chamber 41.

In operation, it is assumed that the power plant unit having the condenser system cnrbodying my invention is operated sometimes at normal or relatively heavy load and at other times at light or substantially no load.

In other words, sometimes the'power-unit merely idles on the line, that is, it has just enough steam admitted to the turbine to rotate the latter without its assuming any part of the load.

During periods of normal load upon the standby unit, cooling water is admitted to both the condensing and cooling sections of the condenser and circulated therethrough.

Under these conditions, the steam entering the condenser from the turbine will be substantially condensed in the outer condensing section while the airand non-condensable gas eous media will flow through the openin s 29 of the battles 27 into the cool-ing section where they will be effectively cooled and any condensable components condensed prior to their removalfrom the condenser.

However, during periods when the standby unit is idling on the line, or carrying substantially no load, a relatively small amount of steam will be exhausted from the turbine into the condenser. If the cooling water is allowed to circulate through the whole tube nest while the turbine is thus operated, the large amount of cooling water being circulated causes the condensate to be cooled to a substantially lower temperature than normal. In order to prevent this substantial depress on in propose to close the valves 37 in the cooling water supply conduits 36 and prevent th admission of water to the condensing tubes, thereby restricting the fii'ow otcooling water to the tubes of the cooling section. The'exhaust steam then passes through and around the temperature of the condensate, 1'

r the condensing section and, instead of being condensed therein, enters the cooling section through the openings 29 in the baffles 27 where both the condensation of the steam and the cooling of the air is accomplished. The restriction of the circulating water to the cooling section during light load reduces the active area of the tubes of the tube nest to substantially that required to condense the relatively small amount of steam entering the V condenser and causes the cooling section to act substantially as the condenser in its entirety under normal operation.-

During such periods of lightload, when water is being circulated through the cooling section of the tube nest, the arrangement in the outlet water box serves to keep the tubes of the condensing section in a floodedcondition, thereby preventing the condensing tubes, while water is not being circulated through them, from becoming unduly heated. This is accomplished by closing the valve 43 which controls the exit connection 42 and by opening the valve 45, which controls the exit connection 44, whereby the water passing through the cooling section is caused to rise to the top of the chamber 41 formed by the. outlet water box and to be discharged from the condenser through the standpipe 46. As a result of this arrangement, the outlet water box will remain filled with water at all times,

dition, maintaining, during all of such times,

times, a static water supply in the condensing tube group.

In testimony whereof, I have hereunto subscribed my name this 9th day of September,

JOHN H. SMITH.

and all of the tubes of the condensing section of the tube nest will be filled with water.

From the foregoing description, it will be understood that I have devised a method of economically operating a condensing system which is efiective to maintain the condensate formed in the condenser at a relatively high temperature even though the system be operated under widely varying load conditions. 7

While I have illustrated and described my invention as applied to one type of condenser, it is to be understood that it is applicable to other types of condensers having means associated therewith to independently control the circulation of cooling water through two or more sections of the tube nest. 1

YVhile I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so'limited, but is susceptible of various; changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. The method of operating a surface condenser which is subjected alternately to full load and light load conditions which includes, during light load conditions, restricting the supply of circulating cooling water to a portion of the tube nest in order to produce condensate of high temperature and, in a d- 

